lustrum

A ceremonial purification of the entire ancient Roman population after the census every five years.

A period of five years.

A lustration or purification; particularly, the ceremonial purification of the whole Roman people, performed at the end of every five years.

Hence A space of five years.

A lustration or purification, especially the purification of the whole Roman people, which was made by the censors once in five years.

A lustration or ceremonial purification of all the ancient Roman people, performed every five years, after the taking of the census.

A period of five years.

a period of five years

a ceremonial purification of the Roman population every five years following the census